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bio 241 [exam #4] > Chapter 18 - Digestive System > Flashcards

Chapter 18 - Digestive System Flashcards

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1
Q

The digestive system is also known as the…

A

GI Tract or Alimentary Canal

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2
Q

What structures are included in the digestive system (not including accessory structures)

A

oral cavity (mouth), pharynx, larynx, esophagus, stomach, small intestine (SI), large intesting (LI), cecum, rectum

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3
Q

What structures does food NOT pass through?

A

accessory structures

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4
Q

What are the accessory structures of the digestive system?

What are all of its general function?

A

teeth, tongue, salivary gland, liver, gall bladder, pancreas

aid in digestion

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5
Q

What is the function of the digestive system?

A

breakdown/digest large biomolecules (carbohydrates, fats, proteins) in food into smaller, absorbable substances (moves into blood vessel)

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6
Q

Give some examples of large biomolecules

What are they broken down into?

Where are the absorbed into?

What is it used by?

A

proteins ➜ amino acids (small) ➜ absorbed into blood stream ➜ used by cells

carbohydrates ➜ monosaccharides (ex. glucose; small) ➜ absorbed into blood stream ➜ used by cells

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7
Q

TRUE or FALSE: Proteins and carbohydrates can be absorbed into the bloodstream

A

False, proteins and carbohydrates are large biomolecules that need to be broken down into small subunits in order to be absorbed into the bloodstream

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8
Q

Why do biomolecules need to be broken down/digested in order to be absorbed?

A

Biomolecules are too large to be absorbed, so they must be broken down into smaller absorbable units

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9
Q

Name the steps of food processing in order

A

ingestion
digestion
absorption
elimination

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10
Q

Describe ingestion

A

taking food into the mouth

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11
Q

Describe digestion

A

TWO TYPES OF DIGESTION

mechanical (physical) digestion: occurs by chewing and stomach muscle contractions

chemical digestion: breaksdown biomolecules into small compounds by chemical reactions; reequires an enzyme

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12
Q

Describe absorption

A

small, broken down substances enter bloodstream; occurs mainly at SI

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13
Q

Describe elimination

A

undigested material exits the body as poop

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14
Q

What part of the digestive system absorbs mostly nutrients?

A

small intestine (SI)

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15
Q

What part of the digestive system absorbs mostly water (H2O)?

A

large intestine (LI)

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16
Q

Name the 2 types of digestion and state where each occurs in the body

A

Mechanical digestion
In oral cavity/mouth by mastication (chewing) of teeth
In stomach by contraction of stomach muscle

Chemical Digestion
In oral cavity/mouth by saliva (salivary amylase)
In stomach by enzyme pepsin

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17
Q

What is mastication and what is its purpose

A

Mastication = chewing

Aids in mechanical digestion to breakdown food into small substances for swallowing and mixes it with saliva

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18
Q

What salivary glands produce saliva?

A

sublingual gland
submandibular gland
parotid gland

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19
Q

What does saliva contain?

A

mostly H2O

mucus

antimicrobial agents (to kill microbes)

salivary amylase (enzyme to breakdown starch/carbs)

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20
Q

What does salivary amylase function in? What does it do?

A

enzyme that helps with chemical digestion

breaks down starches/carbs

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21
Q

Define a bolus. What accessory organ helps form this?

A

bolus: semi-solid ball of material

tongue

22
Q

What serves as a passageway to the esophagus?

A

pharynx (throat)

23
Q

Define deglutition

A

Deglutition = swallowing

24
Q

TRUE or FALSE: The bolus never reaches the stomach if peristalsis is stopped

A

True

25
Q

What tube does the bolus travel through?

A

esophagus

26
Q

Where is the esophagus located?

A

between upper esophageal sphincter (UES) and lower esophageal sphincter (LES)

27
Q

What is the function of the lower esophageal sphincter (LES)?

A

contricts to prevent acid reflux

28
Q

What is peristalsis?

Where does it occur?

A

wave-like muscular contractions that push the bolus from the pharynx and through the esophagus toward the stomach

29
Q

Compare the upper esophageal sphincter (UES) and the lower esophageal sphincter (LES). What can happen if the LES is not tight?

A

UES: between pharynx and esophagus

LES: between esophagus and stomach

If LES not tight, then you can get acid coming up into the esophagus (acid reflux)

30
Q

*TRUE or FALSE: The 3 muscle layers in the stomach wall contribute to mechanical digestion

A

False, only circular and oblique muscles aid in mechanical digestion

31
Q

Where is the stomach located between?

A

between LES and pyloric sphincter

32
Q

What is the purpose of the stomachs inner lining having many folds?

A

it can increase surface area and allow for expansion (in the case that you ate too much food)

33
Q

TRUE or FALSE: No absorption happens in the stomach

A

False, it can perform very little absorption, although it mainly performs digestion

34
Q

What biomolecule does the stomach mainly digest?

A

proteins

35
Q

How many liters of liquid can the stomach expand to carry?

A

2L (gastric juice)

36
Q

Why is gastric juice acidic, and what enzyme is found in the gastric juice?

A

it has lots of H+ because of the enzyme, HCl (used to convert pepsinogen into pepsin)

37
Q

Describe the characteristics of gastric juice (its pH levels, where its produce by, what is contained here?)

A
  • acidic (pH 1-3)
  • produced by gastric pits (deep infolding of stomach lining)
  • pepsin (enzyme that breaks down proteins into AA)
38
Q

What part of the stomach is closest to the LES?

Name the other regions of the stomach and know their general location

A

cardia

fundus
body
pylorus

39
Q

Gastric pits have deep infoldings that lead to ___________ _________ that contain several types of ___________ cells

A

gastric glands (groups of cells in the pit)
secretory

40
Q

What are the different types of secretory cells that make up the gastric glands?

A

mucus neck cells
parietal cells
chief cells

41
Q

What is the function of mucus neck cells?

A

secrete mucus that coats the inner lining to protect the stomach from acid

42
Q

What is the function of parietal cells?

A

secrete HCl (acid)

43
Q

What is the function of chief cells?

A

secrete pepsinogen (inactive form of the protein-digesting enzyme)

44
Q

What is pepsin?

How does pepsinogen (inactive) get converted into pepsin (active)?

A

pepsin is an enzyme that digestive proteins into AA

pepsinogen gets converted into pepsin via HCl (secrete by parietal cells)

45
Q

What would happen if a patient has very litte/few mucus chief cells?

A

they would not have enough mucus to coat the inner lining of the stomach, so they would develop peptic ulcers

46
Q

The acidity of HCl helps to…

A

denature proteins to facilitate digestion

convert pepsinogen into pepsin

47
Q

The stomach contracts (because of muscles) every _______ seconds and ________ food with ______ _______. Is now called acid ______

A

20
mixes (mech. digestion)
gastric juice (chem. digestion)
chyme

48
Q

What is chyme?

A

Is an acidic mix of bolus and gastric juices (located in stomach)

49
Q

Regarding the parietal cell, know which transporter is at the apical surface vs the basal surface. How did the H+ and Cl- get inside the parietal cell? What happens to the HCO3- that is made by the parietal cell?

A

Apical surface: H+/K+ pump (1° AT)

Basal surface: HCO3-/Cl- antiporters (2°AT)

The H+ was made from CO2 and H2O and Cl- was pumped in through the HCO3-/Cl- antiporter

The HCO3- made by the parietal cell moves out into blood capillaries via the HCO3-/Cl- antiporter

50
Q

Does pepsin play a role in mechanical digestion or chemical digestion?

A

Pepsin is an enzyme, so chemical digestion

51
Q

Describe how HCl is produced by parietal cells in the stomach

A

In the parietal cell, CO2+H2O make H2CO3 via CA and then forms HCO3- and H+

At the basal surface, the HCO3-/Cl- antiporter moves HCO3- OUT of parietal cells and into capillaries, which Cl- is moves INTO parietal cell from the capillary

The H+ made earlier in the parietal cell leaves into the lumen of the stomach through the H+/K+ pump (1° AT) at the apical surface

Cl- that moves into parietal cell can diffuse out of the parietal cell and into the lumen of the stomach

HCl is now formed in the lumen of the stomach (part of gastric juice) and can convert pepsinogen (made by chief cells) into pepsin for breakdown of protein into AA :)

bio 241 [exam #4] (3 decks)

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